Polyacetal resins have excellent thermal, mechanical and chemical properties. At the present time, however, since they are relatively expensive, they are mainly used as engineering resins for the manufacture of functional parts.
Looking to the future from the point of view of the raw materials for resins, it is expected that polyacetal resins formed by using methanol as the starting material will become one of the cheapest resins.
Therefore, it is expected that polyacetal resins will be applied even in those fields where ABS resins and the like are now applied, such as, for example, the manufacture of shaped articles decorated by plating and coating. In this field, however, the surface inactivity which is a merit of a polyacetal resin in the conventional uses becomes a defect. Therefore, the surface treatment of polyacetal resins is an important technical problem. By the term "surface treatment" is meant treatment which renders the surface hydrophilic so that plating or coating becomes possible.
It is said that polyacetal resins can be surface activated by etching with a chromic acid mixture, phosphoric acid, sulfonic acid or the like. However, although the surface is roughened by carrying out the etching according to such a conventional method, complete activation is impossible.